EXPLAINER: What is the Ayungin Shoal and why is it important?

It has been eight years since the Permanent Court of Arbitration (PCA) in The Hague, Netherlands invalidated China’s nine-dash line claim over the South China Sea, and yet several maritime zones of the Philippines remain under dispute to this day.

As tensions continue to escalate, GMA News Online took a look at the Second Thomas Shoal, more commonly known as the Ayungin Shoal, which was the subject of the so-called “gentleman’s agreement” between the Duterte administration and China.

What is the Ayungin Shoal?

The Ayungin Shoal — called Ren’ai Reef by China — is a submerged reef in the Spratly Islands, which is a group of more than 100 islands and reefs in the South China Sea.

It is located 105 nautical miles west of Palawan and is within the country’s 200-mile exclusive economic zone (EEZ) and is part of its continental shelf. A country has rights over the economic resources of the sea, seabed, and subsoil to the exclusion of other states within its EEZ.

China, Taiwan, and Vietnam are claiming all the Spratly Islands, including Ayungin, while Malaysia and the Philippines are claiming portions of the Spratlys.

In 2013, the Philippines challenged China’s legal basis for its vast claim in the South China Sea before the PCA.

Three years later, the tribunal concluded that there was no legal basis for China  to claim historic rights to resources within the sea areas falling within the "nine-dash line."

The PCA also found that the shoal “form part of the exclusive economic zone and continental shelf of the Philippines [and] are not overlapped by any possible entitlement of China.”

According to retired Senior Associate Justice Antonio Carpio, there was no “gray area” as the ruling already found that the shoal forms a part of the country’s EEZ.

“Under UNCLOS [United Nations Convention for the Law of the Sea], only the coastal state, only the Philippines can put up a structure there. And no country can stop us from putting up a structure there. China has no right whatsoever to stop us because that’s our exclusive economic zone,” Carpio said.

China however has refused to recognize the PCA ruling.

Why is the shoal important?

Near the shores of Ayungin is a Philippine Navy vessel called the BRP Sierra Madre, which supposedly ran aground in 1999. The ship has become a symbol of Philippine sovereignty in the offshore territory.

In March 2014, former Chinese foreign ministry spokesperson Qin Gang claimed that the Philippines agreed to pull out the BRP Sierra Madre in the same year. 

"A Philippine ship illegally 'grounded' on the Ren'ai Reef of China's Nansha Islands in 1999, with the excuse of 'malfunction.' China made representations right away to the Philippine side who then made unequivocal commitment to towing away the ship," Quin had said.

However, the Department of Foreign Affairs said that the BRP Sierra Madre “was placed in Ayungin Shoal in 1999 to serve as a permanent Philippine installation in response to China's illegal occupation of Mischief Reef in 1995.”

The Mischief Reef or Panganiban Reef is a Philippine-claimed territory in the South China Sea that was occupied by China in 1995.

Attacks

Since the Philippine government established the outpost, the country has been conducting rotation and resupply missions to the BRP Sierra Madre. This has been a source of tension in the disputed waters.

One of the incidents occurred in October 2023, when a China Coast Guard (CCG) vessel bumped with an Armed Forces of the Philippines (AFP)-contracted boat going to the Ayungin Shoal for a resupply mission.

The action was condemned by the National Task Force for the West Philippine Sea (NTF-WPS) as “dangerous, irresponsible, and illegal.”

However, the CCG said it only “lawfully” blocked the Philippine vessels carrying “illegal construction materials” to the BRP Sierra Madre as it claimed “indisputable sovereignty” over Ayungin.

"The Philippines' actions seriously violated the international rules for avoiding collisions at sea and threatened the navigation safety of our ships. Our operations were professional, standardized, legitimate and legal, and the responsibility lies entirely with the Philippines," the statement read.

In March 2024, another Philippine vessel carrying supplies for Filipino troops stationed at the BRP Sierra Madre suffered "heavy" damage after receiving water cannon blasts from CCG ships in its approach to Ayungin Shoal.

The water cannon attack injured three Philippine Navy personnel.

Meanwhile, in June, the AFP released a video showing Chinese agents "snatching" the supplies it airdropped for Filipino troops on BRP Sierra Madre.

Gentleman’s agreement

Amid China’s actions, former presidential spokesperson Harry Roque in March said that then President Rodrigo Duterte entered into a “gentleman’s agreement” with China, which barred the country from sending repair materials to the BRP Sierra Madre.

Roque said the country can only deliver food and water supplies to Filipino troops.

“This is not a secret deal. This was made public by Secretary [Alan Peter] Cayetano na walang gagalaw, walang improvement [sa BRP Sierra Madre], walang problema sa Ayungin," Roque had said.

For its part, the NTF-WPS previously said it was not aware of any agreement between the Philippines and China, and has not seen any document from the former administration that validates or confirms the deal.

Carpio previously said that the agreement was a “disguised surrender” of the country’s EEZ rights as it gave China veto power over the Philippines' exclusive right to erect structures on Ayungin Shoal.

However, former executive Secretary Salvador Medialdea, who served under the Duterte administration, said that the agreement was made in 2013, during the administration of the late President Benigno "Noynoy" Aquino III.

New model

In May, the Chinese Embassy claimed that there is a “new model” arrangement with the Philippine government for managing the situation in Ayungin.

National Security Adviser Secretary Eduardo Año said the claim was "absolutely absurd, ludicrous, and preposterous.”

Meanwhile, the Philippine Coast Guard (PCG) advised the public to refrain from believing China’s statements regarding the shoal, saying the Chinese Embassy is only seeking to justify its “illegal activities” and “aggression.”

Both the DFA and the Department of Justice has sought an investigation into the involvement of foreign diplomats in illegal activities following the leaking of a transcript of an alleged phone call between a Filipino military official and a diplomat of the Chinese Embassy in Manila on the so-called new model.

Check out the two other articles in this series:

EXPLAINER: What is Scarborough Shoal and why is it important?

EXPLAINER: What is the Sabina Shoal and why is it important?

—KG, GMA Integrated News